Although all cells in the human body contain the same genetic material, the same genes are not active in all of those cells. Alterations in gene expression patterns can have profound effects on biological functions. Furthermore, understanding the dynamics and the regulation of gene products (proteins), their variants, and interacting partners is essential in understanding, for example, the mechanisms behind genetic/and environmentally induced disorders or the influences of drug mediated therapies. This understanding can potentially become the underlying foundation for further clinical and diagnostic analyses. Therefore, identifying and quantifying the expression and regulation of genes and/or their products in cells can aid the discovery of new therapeutic and diagnostic targets.
Critical to these studies is the ability to qualitatively determine gene expression and specific variants of whole proteins (e.g., splice variants, point mutations, post-translationally modified versions, and environmentally/therapeutically-induced modifications) and the ability to view their quantitative modulation. Moreover, it is becoming increasing important to perform these analyses from not just one, but multiple target molecules in a cell. The methods available to date still require significant amounts of biological samples or will not provide cell specific information. Additionally, there are limited methods of multiplexed protein measurement technologies due to the additional challenges inherent in protein samples.
Thus, there exists a need for accurate and sensitive detection, identification and quantification of target molecules in every cell of a complex cell population and to retain cell specific information regarding that target molecule.